In a vehicle-mounted radio receiving device, the received electric field strength varies as the vehicle moves. When the received electric field strength of a broadcasting signal is at a strong electric field level, a high-quality radio sound can be outputted because the S/N ratio is good. In contrast, when the received electric field strength is at a weak electric field level, the noise component quantities of a multipath noise and an adjacent interference noise in the broadcasting signal have larger variations than those in the case of an intermediate electric field level or a strong electric field level.
Conventional radio receiving devices include a radio receiving device that makes a broadcast station search in consideration of variations in the noise component quantities of a multipath noise and an adjacent interference noise which correspond to the received electric field strength level of a broadcasting signal. For example, in a broadcasting receiver described in Patent Literature 1, a multipath noise and an adjacent interference noise which are detected from a broadcasting signal are converted into DC voltages, and a summed DC voltage which is the sum of these DC voltage values is used as a trigger signal for a search start. When the received electric field strength of a broadcast is at a weak electric field level, it is determined that the reception state gets worse when the average of the summed DC voltage becomes equal to or greater than a threshold, and a search for a broadcast station is started.